UDC 621.382.2
INVESTIGATION OF HEATING EFFECT ON EFFICIENCY AND LIGHT OUTPUT OF POWERFUL SINGLE CRYSTAL LED SOURCES OF WHITE LIGHT WITH PHOTOLUMINOPHOR
A. E. Chizhikov, Dr. Sc. (Tech.), full professor, RSREU, Ryazan, Russia;
orcid.org/0000-0002-5507-3309, e-mail: сThis email address is being protected from spambots. You need JavaScript enabled to view it.;
M.I. Galitsyn, master student, RSREU, Ryazan, Russia;
orcid.org/0000-0002-5298-6508, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it..
The aim of this work is to identify the main reasons for the decrease in efficiency of «blue» GaN/InGaN chips with quantum wells and light output of powerful single crystal SWL based on them - TDS-P003L4U10 (3 W, 220 Lm), Cree XM-L2 (10 W, 1040 Lm), identification of best operating conditions and development of recommendations to improve SWL quality. The results of measuring relative brightness of chips blue radiation and total brightness of SWL white color formed by the radiation of chip and photoluminophore are presented. Calculation of change in diode voltage was carried out taking into account the dependence of free carriers concentration, band gap, and the density of states on temperature. It was revealed that in TDSP003L4U10 the CVC deviation and decrease in efficiency are caused by increasing (0,6 – 0,86) Om resistance of contact wires connecting the crystal with high-current output with increasing current (temperature) and in Cree XM-L2 – decreasing with increasing series resistance (0,46-0,24) Om of GaN layers (p, n) and substrate. The calculated efficiency value at operating currents for TDS-P003L4U10 (0,7 A) is 0,82, for Cree XM-L2 at the current of 0,7 A – 0,91, and at 3 A – 0,79. The decrease in relative light output is also associated with CVC deviation.
Key words: white light source, blue LED, single crystal, GaN, quantum wells, relative efficiency, theoretical CVC of LED, light output.